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Potential problem with Master (and other Begode Suspension wheels) shock Bridge


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16 minutes ago, Raptor said:

If we delve into the force lines of the structure, an overloading impact on this node can only come from the jamming of the shock absorber. The shock stroke ends before the sliders themselves reach the bottom. If the shock absorber is working normally, such impacts should not occur in the middle of the bridge. Have you measured that the travel of the shock absorber and linkage is at least as long as the sliders!?

Right now my wheel is disassembled and waiting for this part so I can not verify but from memory my shock went all the way up i.e. hitting the rubber bumpers at the top, do you have any better way of measuring? I have a Kuba link with 190x51mm Rockshox shock which I think is a fairly common combination.

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On 1/14/2023 at 11:26 AM, Rawnei said:

Yeah yeah, I don't enjoy creating these topics, I have had so many problems with my Master it's not funny, it's currently disassembled and waiting for below replacement part.

 

I fully understand your pain. After my v1 master and v1 T4 experience it is hard to recommend any begode wheel. My T4 is worst build quality than the master !

Poor master pro owners - there will be even more stress there + Rim problem.

Solution is simple - make bridge U shape. image.thumb.png.967c7a6f7745481d970530fc02490346.png

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  • 2 weeks later...

So I got the replacement bridge yesterday, not a lot of time to fiddle around yet but some quick tests shows that the further up I go on the suspension rods the more friction I get so the rods is not 100% aligned for some reason, I wonder if this is by design or not (i.e. does my wheel have a unique problem or is it like this on all Masters?).

Some background what I mean: I have designed bushings stabilizers that you can see here (https://forum.electricunicycle.org/topic/30029-my-begode-master-3d-printed-accessories/?do=findComment&comment=455926) which removes a lot of slack from the bushings without needing to tighten the screw, installing just one of the sliders at a time with these stabilizers it moves freely up and down the rod with no friction at all, works perfectly and as intended, however as soon as I install both sliders to the bridge the further up I go on the rods the more friction there is meaning the rods are not 100% straight in relation to each other.

A workaround would be to make the stabilizers smaller with less tolerance and more play in the system but that's not solving the root cause why the rods are not completely straight it's just a workaround which adds more play.

Well time to get measuring and testing and being careful not to bend the bridge. 🙄😂

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Can confirm that tolerances are just bad and when you tune the bushings (either by the screws or 3D printed stabilizers) you can not do it one by one you have to do them both in tandem or there will be friction due to poor tolerances in the whole system.

Even just tightening the top screws that hold the pipes to the top frame too much will add friction, the whole construction is pretty finicky.

I've updated my 3D printed bushing stabilizers and made the upper ones a little bit smaller to take this into account.

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6 hours ago, Rawnei said:

Can confirm that tolerances are just bad and when you tune the bushings (either by the screws or 3D printed stabilizers) you can not do it one by one you have to do them both in tandem or there will be friction due to poor tolerances in the whole system.

Even just tightening the top screws that hold the pipes to the top frame too much will add friction, the whole construction is pretty finicky.

I've updated my 3D printed bushing stabilizers and made the upper ones a little bit smaller to take this into account.

Before I read the last post, I was going to tell you that Begode simply manufactured inaccurately and then such a mechanism only works if there is enough tollerance to compensate for the poor manufacturing.

If you are lucky you could compensate for this play at the motor axle. Either grind something away or with shims, depending on whether it is too wide or too narrow, if everything is mounted free of play. 

But I assume that the stabilizer bridge and the upper frame do not match and then your sliders do not run parallel to the axis of the motor. In this case you are fu..ed and no chance to compensate at the motor axle.
You have to use the damn set screw to make your bushing oval. You must accept the left right play in the bushings, but maybe you can eliminate the front rear play a little. 

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6 minutes ago, EUC Custom Power-Pads said:

If you are lucky you could compensate for this play at the motor axle. Either grind something away or with shims, depending on whether it is too wide or too narrow, if everything is mounted free of play.

That would be like throwing a dice and could possibly make things even worse. 😅

The stabilizers are good enough for now, at least they remove a lot of the play.

7 minutes ago, EUC Custom Power-Pads said:

You have to use the damn set screw to make your bushing oval. You must accept the left right play in the bushings, but maybe you can eliminate the front rear play a little. 

Not anymore with my stabilizers you can leave screw unscrewed. 😉👍

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  • 4 weeks later...
On 1/15/2023 at 3:31 PM, Rawnei said:

Thinking more about how they would improve this part it seems more challenging than one could first expect, this part moves up and down between the battery boxes so there is not a whole lot of real estate there to make it thicker, would have to redesign everything or possibly redesign the battery boxes to create more space in between them, might be more complex task to solve than first expected.

Making it taller is not great either that will eat away at the travel length

Did you ever get that replacement part from Begode?
Also, how much disassembly did it take for you to find the issue? I fear I may have run into the same...

My Master was very stiff so I started investigating, and it's locked in a bottomed out position and won't budge. Hoping not to have to take the whole thing apart but it looks like I might have to. 

20230217_144205.jpg

Edited by loofv
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11 minutes ago, loofv said:

Did you ever get that replacement part from Begode?
Also, how much disassembly did it take for you to find the issue? I fear I may have run into the same...

My Master was very stiff so I started investigating, and it's locked in a bottomed out position and won't budge. Hoping not to have to take the whole thing apart but it looks like I might have to. 

20230217_144205.jpg

I had to purchase the part from a reseller, not cheap as Begode are price gauging all their spare parts.

 

Did you try loosening all the bushing screws already? They look tight in the photo.

 

Next step would be disconnecting the batteries and the shock and see how it moves, then removing motor for further troubleshooting.

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3 minutes ago, Rawnei said:

I had to purchase the part from a reseller, not cheap as Begode are price gauging all their spare parts.

 

Did you try loosening all the bushing screws already? They look tight in the photo.

 

Next step would be disconnecting the batteries and the shock and see how it moves, then removing motor for further troubleshooting.

Unfortunate.. So the same part made by Begode but you had to pay for it? Seems like a warranty issue. 

I haven't, are they the 4 big screws between the batteries above the pedal?

Edited by loofv
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14 minutes ago, loofv said:

Unfortunate.. So the same part made by Begode but you had to pay for it? Seems like a warranty issue. 

I haven't, are they the 4 big screws between the batteries above the pedal?

Yes those 4 screws visible on the suspension pillars, try loosening them.

2 minutes ago, Cerbera said:

Why wasn't that covered by warranty just out of interest ?

Chinese Aliexpress seller, "I need this part" "what part is that" "we don't understand" nevermind too late already ordered one, didn't feel like doing that dance again that I had to do for replacment battery pack, not worth the energy. Last time I buy from ali.

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Just now, Rawnei said:

Yes those 4 screws visible on the suspension pillars, try loosening them.

Chinese Aliexpress seller, "I need this part" "what part is that" "we don't understand" nevermind too late already ordered one, didn't feel like doing that dance again that I had to do for replacment battery pack, not worth the energy. Last time I buy from ali.

Thanks for replying!

Yeah that sucks, I guess a retailer would at least chase down the part for you. 

I tried loosening the bushing screws, loosened them all the way pretty much but still nothing. Inflated the shock and that made the wheel make noises, sort of like a house settling, but still the suspension didn't go up. Removing more stuff it is I guess :/ 

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1 minute ago, loofv said:

Thanks for replying!

Yeah that sucks, I guess a retailer would at least chase down the part for you. 

I tried loosening the bushing screws, loosened them all the way pretty much but still nothing. Inflated the shock and that made the wheel make noises, sort of like a house settling, but still the suspension didn't go up. Removing more stuff it is I guess :/ 

Yep, you need to take it apart and troubleshoot more now, disconnect all the batteries so you have room to work.

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On 2/17/2023 at 4:18 PM, Rawnei said:

Yep, you need to take it apart and troubleshoot more now, disconnect all the batteries so you have room to work.

Update: I disassembled the wheel to figure out what wasn't working, and finally found that the left fork leg in the suspension was completely seized. After taking it apart further I found that there was a TON of dirt and sand built up in the entire suspension, in between the rods and the legs etc. I cleaned it out as much as I could with water, WD-40, steel wool etc. I was unable to get the stabilizer bushings out, they were completely stuck due to the dirt. But using steel wool I was able to sand the dirt down enough to get the suspension to move again :D So all is well! Thanks for your help! 

20230218_153318 (1).jpg

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Thanks for the update, but that's a bit double wank and shit chips; mud isn't supposed to be getting up there ! What's that centre mudguard doing ? Not enough by the looks of it ! OK I can see I need to add this check to the other 20 or so we have to do every few hundred miles or so...

Edited by Cerbera
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1 minute ago, Cerbera said:

Thanks for the update, but that's a bit double wank and shit chips; mud isn't supposed to be getting up there ! What's that centre mudguard doing ? Not enough by the looks of it !

Agreed, that thing is useless haha. So is the small "external" mudguard as well. Though it was probably my fault, i dropped it in mud on the left side about a month ago, I think since then it's slowly been getting worse. Also Swedish road conditions in winter are not the best. 
But one would hope that Begode could conjure up a less symbolic mudguard in the future! 

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What could we do, if anything to reinforce that ultra thin bit by the screw ? There is no physical room to add more material. I guess... nothing ?! Try and shop around for spares ! My dealer was talking about commissioning some mega-grade steel replacements, but I imagine they'll only do that if they get more than 1 or 2 issues with the stock setup...

Edited by Cerbera
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8 minutes ago, Cerbera said:

What could we do, if anything to reinforce that ultra thin bit by the screw ? There is no physical room to add more material. I guess... nothing ?! Try and shop around for spares ! My dealer was talking about commissioning some mega-grade steel replacements, but I imagine they'll only do that if they get more than 1 or 2 issues with the stock setup...

Yeah, it's very poorly designed.. Though I would imagine that one would probably be fine in most cases even if it cracks, I think Rawnie got unlucky. If the other bolt still holds then I think it will probably stay straight with the rest of the construction. 

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29 minutes ago, loofv said:

Update: I disassembled the wheel to figure out what wasn't working, and finally found that the left fork leg in the suspension was completely seized. After taking it apart further I found that there was a TON of dirt and sand built up in the entire suspension, in between the rods and the legs etc. I cleaned it out as much as I could with water, WD-40, steel wool etc. I was unable to get the stabilizer bushings out, they were completely stuck due to the dirt. But using steel wool I was able to sand the dirt down enough to get the suspension to move again :D So all is well! Thanks for your help! 

20230218_153318 (1).jpg

Damn, that explains it!

26 minutes ago, loofv said:

I can also add that my bridge was not cracked, but it's showing some wavy patterns in the metal in the weakest spot (bottom right near the bolt). 

20230218_201657.jpg

Yeah I think cracking is very unusual, I cracked mine by hand but have to watch out for flexing (probably also unusual).

21 minutes ago, Cerbera said:

What could we do, if anything to reinforce that ultra thin bit by the screw ? There is no physical room to add more material. I guess... nothing ?! Try and shop around for spares ! My dealer was talking about commissioning some mega-grade steel replacements, but I imagine they'll only do that if they get more than 1 or 2 issues with the stock setup...

They (Begode) could easily add 1-2mm more on that part, there's space between the battery boxes, considering it's 0.7mm in places now 1-2mm more would be quite a big upgrade.

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